num = 5     
if num == 3:            # 判断num的值
    print ('boss')        
elif num == 2:
    print ('user')
elif num == 1:
    print ('worker')
elif num < 0:           # 值小于零时输出
    print ('error')
else:
    print ('roadman' )    # 条件均不成立时输出


print ("python 复合布尔表达式计算采用短路规则")
a=0
b=1
if ( a > 0 ) and ( b / a > 2 ):
    print ("yes")
else :
    print ("no")

# a=0
# b=1
# if ( a > 0 ) or ( b / a > 2 ):
#     print ("yes")
# else :
#     print ("no")



var = 99 
 
if ( var  == 100 ) : print ("变量 var 的值为100") 
 
print ("Good bye!")


a = [1,2,3]
b = a if len(a) != 0 else ""
print(b)

c=[]
d = c if len(c) != 0 else "c 是一个空列表"
print(d)


